Electron tube



April '13, 1926. 1,580,446

J/SLEPIAN ELECTRON TUBE Filed April 21. 1921' WITNESSES; lNV ENTOR Jsep2z $ie T022.-

Patented Apr. 13, 1926.

UNITED" STATES I Josnr PATEN'l OFFICE.

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' ELECTRON" TUBE.

Application filed April 21, 1921. Serial No. 463,208.

To all whom it may concern:

Be it known that I, JOSEPH SLEPIAN, a citizen 'ofthe United States, and 'a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, haveinvented a new and useful Improvement in Electron Tubes, of which the following is a s ecification.

y invention relates to electron tubes and more especially to externally controlled electron tubes which may function as audiofrequency amplifiers in wireless receiving systems.

One object of my invention is to provide an externally controlled electron tube of such construction that it may be employed as an audio-frequency amplifier for weak, as well as strong, signal impulses.

Another object of my invention is to provide an anode of such structure that the number of positive ions formed in the tube may be materially reduced.

'In the operation of externally controlled.

tubes as audio-frequency amplifiers, it has been found that the o eration ofsuch tubes has been adversely a ected by the attraction of positive charges to the inner surfaces of the walls of the tubes immediately adjacent the external control electrodes. According to my invention, I prevent the attraction of the positive charges to the inner surface of the glass adjacent the electrode by shielding such portions of the tube, as hereinafter described.

The desired result may be accomplished by employing an elongated three-electrode tube which has a restricted portion for dividin the tube into two chambers, the hotcatho e being disposed in said restricted portion, the anode in one chamber and the control electrode immediately adjacent the exterior surface of the remaining chamber. As may readily be seen, by reason of the narrowness of the neck, which is formed by the constriction of the tube, the presence of the filament therein and the high density of the electrons in the space immediately surrounding the filament, the ions, most of which are produced in the chamber containing the anode, areprevented from reaching the interior surface of the chamber immediately-adjacent the control electrode.

Other objects, as well as details of construction, whereby my invention may be practiced, will be apparent from the following description, taken in connection with the accompanying drawings and claims,

wherein:

The single figure in a diagrammatic representation of circuits and apparatus embodying my invention. 1

Referring to the drawing, I have shown, for purposes of illustration, a simple receiving circuit for spark signals and, in

addition, means for amplifying the effects of such signals. The receiving system just mentioned comprises an antenna circuit, which includes an antenna 1, a variable inductance coil 2 and aground Ie',ad.3, and a detector circuit, which is connected in shunt to the variable tuning coil 2 and which includes a detector'-of well-known form. a

The rectified impulses traversing the detector 4 may be amplified by means of an electron tubev 5 which comprises an elongated container 6' having a constricted portion 7 for dividing the container into two chambers 8 and 9, respectively. A filament 11, which may be energized by means of a source of energy 12 through a variable resistor 13, is disposed within the concomprises a source of energy 18 and an indicating device 19.

It is, apparent, of course, that the 'par ticular arrangement of circuits shown in the drawin forms no part of my invention,

they being shown and'described merely to I illustrate one system in which the electron tube 5 may be employed.

\Vhen an alternating electromotive force is impressed upon the grid 15, the inner surface of the walls of the tube immediately adjacent the external electrode 15 become charged negatively to a value depending upon the magnitude of the positive halfwaves of the alternating electromotive force. The effect of such negative charges is to produce a negative bias of the external electrode with respect to the effect of subsequently impressed electromotive forces.

I have found, however, that, when emplo ing such tubes as audio-frequency an pli ers, the neutralizing effect of the positive ions, which are formed during the normal operation of the tube, upon the negative charges on the inner surface of the walls of the tube immediately adjacent the control electrode vmay be such as to render the-tube less sensitive to impulses of an audible frequency. By employing a tube as hereinbefore described, I have been able to maintain the negative bias for relatively long periods of time.

The number of positive ions in the chamher 8, which are formed by reason of the collisions of high-speed electrons with molecules of gas contained therein, may be very materially lowered by reducing the volume of gas through which the electrons pass after they have attained high-speed. Such results may be accomplished in my invention by employing a filamentary anode of relatively small dimensions, as shown in the drawing.

In operation, upon the receipt of incoming signal impulses, alternating electromotive forces are impressed upon the terminals of the rectifying device 1. The action of the rectifying device 4 is to impress unidirectional electromotive forces upon the grid 15 which, in turn, effects amplified variatlons in the currents traversing the plate-filament circuit. The fluctuations of the currents in the plate-filament circuit may be detected by the indicating device 19.

One advantage of my invention is the provision of means whereby externally-controlled vacuum tubes may be rendered equally sensitive to relatively strong or weak signals when employed as audio-frequency amplifiers.

Another advantage of my invention is the provision of means for maintaining the control electrode at a substantially permanent negative bias by decreasing the rate of leakage of the negative charge from the interior surface of the walls of the tube immediately adjacent the external electrode.

Vhile I have shown only one embodiment of my invention, it is capable of various changes and modifications in the arrangement of circuits emplo ed, and in the structure of the electron tu e, without departing from the spirit of my invention. I desire, therefore, that only such limitations shall be imposed thereupon as are indicated in the appended claims. I

I claim as my invention:

1. An evacuated electric device comprising a container having a restricted portion for dividing said container into two chambers, means tending to cause the passage of ions from one chamber to the other and means disposed in said restricted portion for retarding the passage of said ions from one chamber to the other, said la1t-mentioned means comprising a source of electron emission 2. An evacuated electric device comprising a container having a restricted portion,

a source of electron emimion disposed immediately adjacent said rewricted portion and an anode and a control electrode oppositely disposed with respect to said restricted portion.

3. An evacuated electric device comprising a container having a restricted portion for dividing said container into two chambers, a hot cathode disposed in said restricted portion whereby a dense negative electrostatic field may be produced therein, an anode disposed in one chamber and a control electrode disposed immediately adjacent the exterior surface ofthe remaining chamber.

4. An evacuated electric device comprising a container having a restricted portion for dividing said container into two chambers, a space-current path within said evacuated electric device, electrodes individual to said space-currentpath, one of said electrodes being disposed in the restricted portion and another of said electrodes being disposed in one of said chambers on one side of said restricted portion and a control electrode disposed on the opposite side of said restricted portion, said control electrode being so disposed that the field of force therefrom is substantially parallel to said space-current path.

5. An evacuated electric device comprising a container having a restricted portion for dividing said container into two chambers, a space-current path within said evacuated electric device, electrodes individual to said space-current path, said electrodes comprising a hot cathode and an anode, the hot cathode being disposed in said restricted portion and the anode being disposed in one of said chambers and a control electrode so disposed immediately adjacent the external surface of the remaining chamber that the field of force therefrom is substantially parallel to said space-current path.

6. An electron tube including a container havin' a restricted portion for dividing the tu e into two chambers, an anode and a control electrode oppositely, disposed with respect to-said restricted portion and a cathode cooperating therewith.

7. An electron tube including a container having a restricted portion for dividing the tube into two chambers, a cathode, an anode disposed in one of said chambers, and a control electrode disposed externally of the inner wall of the other chamber.

8. In a vacuum tube, a source of electrons, an anode, and means for giving the electrons a velocity toward said anode, said anode being of small area compared to the cross-section of the electron stream part way between said source and said anode, whereby the volume of gas through which the electrons pass at a velocity sufiicient for ionization is minimized.

9. An electron tube comprising an enclosing vessel, a cathode and a filamentary anode therein, and means including an externally disposed electrode for producing a controlling electrostatic field.

10. An electron tube comprising an enclosing vessel, a cathode and a filamentary anode constituting two internal electrodes therein, and means including an externally disposed electrode for producin trostatic'field, one of said internal electrodes a controlling elecbeing disposed between said external elec trode and the other internal electrode.

11. An electron tube com rising an enclosing vessel, a cathode and a lamentary anode therein, and means including an externally disposed electrode for producing a controlling electrostatic field, said cathode being disposed between said external electrode and said anode.

I 12. An electron tube comprising a container having a restricted portion therein, a cathode within said container near said restricted portion, an anode disposed on one side of said cathode, and means including an external electrode disposed on the opposite side of said cathode for producing a controlling electrostatic field.

13. An electron tube comprising a container having a restricted portion therein, a cathode within said container near said restricted portion, a substantially stright filamentary anode disposed on one side of said cathode, and means including an external electrode disposed on the opposite side of said cathode for producing a controlling electrostatic field.

In testimony whereof, I have hereunto subscribed my name this 14th day of April, 1921.

JOSEPH SLEPIAN. 

